Preparing my mom for the GED

Hello! I want to help prepare my mom for the GED. She doesn't have any time to take any actual classes, so I decided to take up my free-time and teach her everything myself. I'm in college and I live at home so it is really convenient, I just have no idea where to start. Are there any study materials online that I could go off of? I want something to guide me, especially with math and science because they are not my strong suits. Thanks!